Phenotypic analysis of CD4⁺CD8⁺ thymocytes from H-2^b H-Y and H-2^b 2C mice with the CD2 null mutation. Thymocytes from H-2^b H-Y or H-2^b 2C mice with or without the CD2 null mutation were stained with PE-labeled anti-CD4, FITC-labeled anti-CD8, and biotinylated MoAb to the indicated marker followed by Streptavidin Tricolor and analyzed in the FACScan flow cytometer. A total of 30,000 events were collected. The fluorescence level of the indicated molecule on gated CD4⁺CD8⁺ thymocytes with (dotted line) and without (solid line) the β₂-microglobulin null mutation (β₂m^o) is shown.